The present disclosure relates to a non-aqueous solvent, electrolyte compositions using the non-aqueous solvent, and a non-aqueous electrolyte secondary battery. More particularly, the present disclosure relates to a non-aqueous solvent containing ethylene carbonate, propylene carbonate, and diethyl carbonate, non-aqueous electrolyte compositions containing the non-aqueous solvent and an electrolytic salt, and a lithium ion non-aqueous electrolyte secondary battery using the non-aqueous electrolyte compositions.
In recent years, many portable electronic apparatuses such as camera-integrated type VTR (video tape recorder), digital camera, cellular phone, personal digital assistant, notebook-sized computer, and the like have been put into the market. Miniaturization and a light weight of such a portable electronic apparatus have been realized. As portable power sources for such electronic apparatuses, studies and development to improve an energy density are vigorously being progressed with respect to batteries, particularly, secondary batteries.
Among them, a lithium ion secondary battery in which carbon is used for an anode active material, a lithium-transition metal composite oxide is used for a cathode active material, and a carbonic ester mixture is used for an electrolytic solution has widely been put into practical use because a large energy density can be obtained as compared with a lead battery and a nickel cadmium battery as non-aqueous system electrolytic solution secondary batteries in the related art (for example, refer to JP-A-1992(Heisei 4)-332479).
Particularly, as for a laminate battery using an aluminum laminate film for a sheathing, an energy density is large because the laminate battery is light (for example, refer to the Official Gazette of Japanese Patent No. 3482591).
In such a laminate battery, if a polymer swelled by an electrolytic solution is used, since a deformation of the battery can be suppressed, a laminate polymer battery is also widely used (for example, refer to JP-A-2000-133215).
However, since a density of an electrode active materials provided for each of electrodes is increasing and a gap between them is decreasing in association with the recent realization of a high capacitance of a battery, in an electrolytic solution in the related art, conductivity is insufficient and lithium ions are difficult to move between the electrode.
There is, consequently, such a problem that battery performance deteriorates largely and a discharge capacitance maintaining ratio at the time of the repetitive charge and discharge decreases.
It is, therefore, desirable to provide a non-aqueous solvent which can improve a discharge capacitance maintaining ratio at the time of the repetitive charge and discharge, electrolyte compositions using such a non-aqueous solvent, and a non-aqueous electrolyte secondary battery.